DDT and pyrethroids: Receptor binding and mode of action in the house fly |
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| Authors: | CP Chang FW Plapp |
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| Institution: | Department of Entomology, Texas A&M University, College Station, Texas 77843 USA |
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| Abstract: | The mode of action of DDT and pyrethroids was investigated in the house fly, Musca domestica L, using drug:receptor binding techniques. Both in vivo and in vitro binding studies demonstrated the existence of membrane receptors which bind specifically to 14C]DDT and 14C]cis-permethrin. The receptors show properties to be expected of a critical target site of these insecticides. These include negative temperature correlation with binding, relatively nonsensitivity to DDE, and sensitivity to Ca2+. The receptor sites are readily saturated at 45–90 nM 14C]DDT and have an apparent disassociation constant (Kd) of 12.2 nM. The maximum number of binding sites was estimated to be 17 pmol DDT/mg membrane protein (0.34 pmol/house fly head). Competition studies showed DDT, cis-permethrin, and cypermethrin bind to the same receptor but not at precisely the same site. The addition of Ca2+ to the incubation buffer significantly inhibited the binding of both 14C]DDT and 14C]cis-permethrin, suggesting the receptor binding is Ca2+ sensitive and may have a role in ion conductance. |
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